A higher resting heart rate is associated with a higher risk for all-cause and cardiovascular mortality, even in those without traditional risk factors for cardiovascular disease, according to a meta-analysis published online November 23 in CMAJ.
"Results from this meta-analysis suggest the risk of all-cause and cardiovascular mortality increased by 9% and 8% for every 10 beats/min increment of resting heart rate," write Dongfeng Zhang, MD, PhD, from the Department of Epidemiology and the Department of Health Statistics, Medical College of Qingdao University, Shandong, China, and colleagues. "The risk of all-cause mortality increased significantly with increasing resting heart rate in a linear relation, but a significantly increased risk of cardiovascular mortality was observed at 90 beats/min...consistent with the traditionally defined tachycardia threshold of 90 or 100 beats/min for prevention of cardiovascular disease."
To better define the association between resting heart rate and mortality, the researchers searched PubMed, Embase, and MEDLINE databases through January 1, 2015, identifying 46 studies that met their inclusion criteria of English or Chinese articles reporting findings from general population prospective studies. The studies needed to measure resting heart rate and all-cause or cardiovascular mortality outcomes with adjustments for age or multiple other factors.
The data set included more than 1.2 million patients and 78,349 all-cause deaths from 40 studies. Data specific to cardiovascular mortality included 848,320 patients and 25,800 deaths from 29 studies. Duration of follow-up across the studies ranged from 3 to 40 years.
The authors found that those with a resting heart rate of 60 to 80 bpm were 12% more likely to die from any cause and 8% more likely to die from cardiovascular causes compared with those with a resting heart rate of 45 bpm (RR, 1.12 [95% CI, 1.07 - 1.17], and RR, 1.08 [95% CI, 0.99 - 1.17], respectively). The risk became 45% greater for all-cause mortality and 33% greater for cardiovascular mortality among patients with a resting heart rate greater than 80 bpm (RR, 1.45 [95% CI, 1.34 - 1.57], and RR, 1.33 [95% CI, 1.19 - 1.47], respectively).
Adjusting for traditional cardiovascular disease risk factors did not substantially change the findings: All-cause mortality risk increased significantly in a linear fashion as resting heart rate increased when compared with a resting rate of 45 bpm, but risk for cardiovascular death increased significantly at a resting rate of 90 bpm. This threshold is "consistent with the traditionally defined tachycardia threshold of 90 or 100 beats/min for prevention of cardiovascular disease," the authors note.
"One main concern lies in whether a high resting heart rate is an independent predictor, because higher heart rates coexist with traditional risk factors of cardiovascular disease and poor health status," the authors point out. "Overall, the association of resting heart rate with risk of all-cause and cardiovascular mortality is independent of traditional risk factors of cardiovascular disease, suggesting that resting heart rate is a predictor of mortality in the general population."
They note that previous research has identified a link between resting heart rate and outcomes in patients with renal disease, erectile dysfunction, and pulmonary hypertension, and even noncardiovascular conditions such as chronic obstructive pulmonary disease. In addition, findings from trials with ivabradine, which reduces heart rate, "suggest that the association of heart rate reduction with outcomes may differ among populations of different risk, and higher heart rate is due to different pathophysiological mechanisms in different conditions," the authors write.
Among the study's limitations were the potential for publication bias and heterogeneity among the studies, including differences in the covariates considered and the way they were adjusted.
"Further studies are warranted to develop a prediction algorithm that would consider both resting heart rate and classic cardiovascular risk factors to allow physicians to use resting heart rate in clinical settings," the authors conclude.
The authors have disclosed no relevant financial relationships.
CMAJ. Published online November 23, 2015. Full text
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